Lighting unit.



E, ,F. GUTH,

LIGHTING uwn.

APPLICATION FILED AUGJB. [917- Patented Feb. 18,1919.

IN V EATOR llli till MISSOURI.

LIGHTING UNIT.

Specification of Letters Patent.

flatcnted Feb. 113, Tildi'li.

Application filed August 18, 1917. Serial No. 186,861.

To all whom it may (on/1 1m:

Be it known that I. EDWIN F. Geri-I, a citizen of the United States ofAmerica, residing at the city of St. Louis, State of Missouri, UnitedStates of America. have invented a certain new and useful Lighting Unit,of which the following is such a full, clear, and exact description aswill enable any-one skilled in the art to which it appertains to makeand use the same, reference being had to the accompanying drawings,forming part of this specification.

My invention relates to a light controlling device embodying means forreflecting and diffusing rays of light emanating from a source ofillumination, and means for corn trolling said rays to eiiicientlyutilize them for the illumination of the space where light is requiredfor useful purposes, which is sometimes referred to as the workingplane. A further object of the invention is to produce a lightcontrolling device of simple and inexpensive construction, which willachieve the purposes above outlined, and which will also permit aportion of the light to pass toward the ceiling and sufiicientlyilluminate it to avoid the formation of shadows thereon.

.A light controlling device or shield embodying my invention isillustrated in the accompanying drawing. In the preferred form ofconstruction the shieldis made of glassin one piece, the upper portion 1and the lower portion ,3 being of translucent glass, and the centralportion 2 being transparent and provided with prismatic surfaces asshown. The lip provides convenient means for attachment of a holder orother supporting or suspending device. The lamp 4 is preferablypositioned below the plane of the lower portion of the prismatic sectionand preferabl within the translucent portion 3. Laterally and downwardlydirected rays of light from the source pass through the translucentportion 3 and are difi'used thereby, whereas upwardly directed rays oflight strike the upper portion 1 of the shield, which, whiletranslucent,has its under-surface polished or otherwise treated whereby much of thelight will be reflected, and the position of this surface is suchwithreference to the position of the surface of the prismatic portion 2 thatthe reflected rays are directed to the prismatic portion. The prisms arepreferably arrangedto refract these reflected rays outwardly, that is tosay, increase their inclination with respect to a horizontal planepassing through the light source, and thus increase the totalillumination in the area to which they are directed. which area is lessstrongly illuminated by the light passing through portion than is thearea immediately beneath and adjacent to said portion. I thusetlect acomparatively even distribution of light over an area of the workingplane which is larger than the area of even distribution which wouldexist if none of the upwardly directed rays of light from the sourcewere directed back to the working plane, 'or than if these rays were notdirected outwardly at a greater angle th an their angle of reflectionfrom the reflector above the light.

In addition to their function of controlling the direction to. thereflected rays, the prisms in the portion 2 of the shield prevent imagesof the lamp filament, appearing in the reflector 1, from being visible.

As previously indicated, I prefer to em ploy such material andreflecting surface for the portion 1; of the shield as will ermit somelight to pass directly throng this portion to the ceiling, butpreferably also limiting the amount of light to the ceiling tosufficient to prevent the formation 0 shadows of the fixture itself, orof other fixtures thereon, in orde that the major portion of the lightmay be directed in the shortest path possible to the useful or worle ingplane, and the useful eficiency of the unit be made as high as possible.For eX- ample, the portions 1 and 8 may be made of what is known in thetrade as enameled glass and the portion 1 may be providedwith a heaviercoating of enamel than the portion 3.

Modifications in structure and arrange ment are possible, and it will beunderstood that I do not intend that the scope of my invention belimited to the preferred form herein described.

Having fully described my invention,

what I claim as new and desire to secure by Letters Patent of the UnitedStates is:

l. The combination with a source of light,

of a translucent shield on one side of a plane of the light, lightreflecting means on the opposite side of said plane, and retractingmeans for altering the direction of the refiected rays, said reflectingand refracting means being positioned to give refracted rays a generaldirection corresponding to prismatic portion, and a source of lightwithin the shield, the prismatic portion being above thesource of lightso positioned relative thereto that the direct rays therefrom do notimpinge upon its inner surface, and means to reflect light from thesource to the prismatic portion.

3. In combination, a light controlling shield having a prismatic portionand a translucent portion below'the prismatic portion, a source of lightwithin the translucent portion, and means for directing rays of lightfrom said source to the prismatic portion.

4:. The combination with a source of light, of a light controllingshield inclosing said source, said shield having a prismatic central"portion and translucent upper and lower portions.

5. The combination with a source of light, of a light controlling shieldinclosing said source, said shield having a prismatic central portionand translucent upper and lower portions, the upper portion beingpositioned to reflect light from the source to the prismatic portion.

6. In combination a unitary glass shield having its upper anch lowerportions formed of translucent glass and its central portion ofprismatic glass, and a source of light within the shield, the upperportion of the shield being positioned and adapted to refiect light tothe prismatic portion.

7. In combination, a unitary glass shield having its upper and lowerportions formed of translucent glassand its central portion of prismaticglass, and a source of light in the lower portion, the upper portion ofthe shield being positioned and adapted to reflect light to theprismatic portion.

8. In combination, a unitary glass shield having its upper and lowerportions formed of translucent glass and its central portion ofprismatic glass, a source of light in the lower portion, the upperportion of the shield being positioned and adapted to reflect light tothe prismatic portion, and the prismatic portion being adapted to changethe direction of the reflected rays to increase their angle with respectto'a horizontal .plane through the source of h ht. In testimony whereofI have liereunto set my hand and afiixed my seal.

EDWIN F. GUTH.

